1. Field of the Invention
This invention relates generally to an apparatus, system and method of ionized air rinsing of containers, and more specifically to the rinsing of such containers without use of water, brushes or other elements that come into direct contact with the containers.
2. Background Art
Empty containers, such as PET bottles, intended for filling with a liquid beverage typically become contaminated with foreign material, such as paper and wood dust, during shipping, even when they are stored in boxes or other carrying receptacles and also as they are being processed prior to filling. In the latter case, contact between the containers and the surfaces of articles, such as conveyors or carriers, used to convey the containers, cause them to pick up a small amount of net electrostatic charge, thereby rendering them capable of attracting fine particles to the containers' internal and external walls. Thus, the need to rinse or otherwise clean the containers prior to filling is necessary to ensure that the beverages are acceptable to the ultimate consumer.
The dust particles contaminating these containers are characteristically extremely small, often measuring less than 10 microns in diameter. Any electrostatic charges on the containers induce opposite charges on the particles to attract and hold them on the containers' walls. To remove particles adhering to the walls, these opposite charges must be neutralized. Neutralizing the charges is difficult, however, because the charges holding each dust particle to a container's wall are shielded by the dust particle itself. Moreover, once the electrostatic forces have been momentarily abated, the freed dust particles must be removed immediately before they re-attach themselves to a container.
Several methods have been used to provide a thorough cleaning of the inside of a bottle. In the prior art methods, the processing of empty containers in preparation for filling them with beverages and the like included spraying the containers with water. This cleaning technique, however, fails to remove all of the dust particles inside the containers unless extraordinary measures are taken. Moreover, the high humidity generated by the water sprays favors the growth and spread of microorganisms, creating additional problems in the typical factory environment.
Other methods utilize a hot water rinse directed into a bottle having a downwardly facing opening, wherein a large number of bottles are being transported through a conveyor system at a high rate of speed. An example of such a cleaning arrangement is disclosed in U.S. Pat. No. 5,363,866. A jet nozzle arrangement is taught which provides an aeration and distribution of a cleaning agent at successive stations in the conveyor line.
The use of hot water or chemical disinfectants typically has been considered unsuitable for rinsing PET bottles prior to filling because hot water or disinfectants may chemically or physically alter the characteristics of PET bottle material. Such alterations could render the bottles unsuitable for containing beverages, or may adversely affect the quality or taste of the beverage, or may even render the beverage unsuitable for human consumption.
Various devices and processes not using unsuitable chemicals or excessively hot water have been proposed for sanitizing containers such as bottles. For example, devices using ozone or ozonated water as a sanitizing agent have been proposed. Ozone is highly reactive and is an effective oxidizing agent for sanitizing containers. Ozonated rinse water is preferable to untreated rinse water because it may be effective in removing microbes and other contaminants without changing the chemical or physical nature of the container. For example, Silberzahn U.S. Pat. No. 4,409,188 proposes a device for sterilizing containers that comprises a rotatable immersion wheel for immersing the containers in a bath of ozone and water. Hughes U.S. Pat. No. 5,106,495 proposes a portable water purification device using ozone as a treatment agent circulated by a pump through a venturi where the ozone is injected into the water, which is then returned to the tank after cleaning. However, the use of water or other liquid rinse media slows the rinsing process as a result of the need to dry or otherwise remove the liquid from the container prior to filling, which takes time and slows down the container preparation and filling procedure.
Another consideration of those prior art methods and systems that have a fluid or jet stream that is directed into the container, and especially those which intrude thereinto by inserting a nozzle or other means of producing a jet flow into the enclosure of the container itself, is that there is a possibility for introduction of extraneous matter and/or contamination into the bottle, which presently requires measures to avoid the possibility of such contamination. Additionally, methods which require the insertion of a nozzle into a container complicate and slow the cleaning process, because the container must be aligned fairly precisely with the nozzle and held in position for some period of time.
Other methods for cleaning containers of dust and debris, and more specifically, cleaning of plastic or PET bottles, are known, but most of these are similar to those prior art methods and systems described above. Ionized gas streams injected into upside down containers are taught in U.S. Pat. No. 4,208,761 to Ionescu and U.S. Pat. No. 5,265,298 to Young. The latter patent teaches a series of ionized nozzles staggered with intervening vacuum collectors to enable capture of ionized dust particles immediately after they have been “loosened” from the internal surface of a container. It should be noted that the ionized nozzles are expensive, and a configuration having only ionized nozzles in a long container cleaning station will cause the complete container cleaning system to be overly expensive. In addition, U.S. Pat. No. 5,265,298 does not have any type of guard or means to maintain a clearance between the nozzles and the fast moving containers that are sped past on guard rails. Accordingly, it becomes possible that misalignment of the elements of the system may cause the displacement of one or more nozzles such that a container that is skewed may collide with the nozzle at a high rate of speed, thus causing damage not only to the container but perhaps also to the nozzle, and shutting down the container processing line for repairs for a considerable period.
What is needed is a cleaning procedure that is efficient, effective, relatively inexpensive and does not produce undesirable effluents or other residual elements, such as rinse water residue, while simultaneously providing resource conservation and sustainability. A configuration that protects the sensitive elements of the system is also desirable to reduce down time and expensive replacement parts of the system.